Resumo

GONZALEZ LEGARDA, Edgar Andrés; DUQUE NIVIA, Guillermo  e  ANGEL SANCHEZ, Diego Iván. Environmental changes in water and sediments by aquaculture in floating cages in Guamuez Lake, Nariño, Colombia. Acta Agron. [online]. 2022, vol.71, n.1, pp.22-28.  Epub 24-Abr-2023. ISSN 0120-2812.  https://doi.org/10.15446/acag.v71n1.98924.

Aquaculture supplies the production of animal protein in a profitable and sustainable way; however, it can generate changes at an ecological and environmental level. In this study, changes in water quality and sediments related to rainbow trout (Onchorhynchus mykiss) farmed in the RAMSAR - Guamuez Lake wetland, during high and low rainfall, were determined, comparing six zones with three replications and at three depths. Physicochemical and nutrient parameters in water and sediments were measured, performing analysis of variances and determining significant differences. The physicochemical parameters of the water presented less favourable values for the farming companies as opposed to control points, mainly in the upper part of the lake where there is a greater influence of anthropic activities. Aquaculture processes not only alter the quality of the water, but also, other anthropic activities; however, values were within acceptable ranges for aquaculture as well as for the ecology of the lake. Sediments act as a deposit of aquaculture residues, presenting symptoms in the physicochemical and nutrient parameters measured in the farming companies, mainly total phosphorus and total nitrogen, which presented acceptable ranges; however, their increase could cause eutrophication problems in the lake. The increase in rainfall contributes to pollution increase through tributaries and runoff that finally deposit contaminants in the lake; therefore, aquaculture is only one of the factors that can negatively affect a lentic aquatic system.

Palavras-chave : Water quality; pollution; nutrients; physicochemical parameters; rainbow trout.

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